Question

how many spheres of equal volume can be made with radius R/2 each if a sphere or radius is melted

Answer 1

Let the radius of hemisphere be R and radius of sphere be r

$\\ \bf ∵ volume \: of \: hemisphere = \frac{2}{3}\pi\ r ^{3} \\\bf also, volume \: of \: sphere = \frac{4}{3}\pi \ r^{3} \\\bf according \: to \: the \: question, \\\bf \frac{2}{3}\pi\ r ^{3}= 4 ×  \frac{4}{3}\pi \ r^{3} \\ \bf R^{3} = 8r^{3} \\\bf ∴ R = 2r \: units$